The following excerpt is from: here
The toxic chemicals released by air fresheners –particularly those with pine, orange and lemon scents – are known as volatile organic compounds VOCs. These are well-proven toxins, many of which have been linked to a range of diseases and conditions when being inhaled even in low concentrations over a long period of time.
Some of these chemicals include benzene, petroleum-derived chemical, which causes cancer in animals and has been linked to leukemia; xylene, which has been linked to nausea and sick building syndrome, as well as liver and kidney damage; phenol, which can cause kidney, respiratory, neurological and skin problems; naphthalene, a suspected carcinogen, which has been linked to blood, kidney and liver problems; and formaldehyde, a colorless, unstable gas. Inhaling formaldehyde fumes in even small amounts can cause coughing, a sore throat, and respiratory and eye problems. Formaldehyde has been linked to cancer, particularly in the nasal cavity.